Rheology of confined non-Brownian suspensions

TL;DR

This paper investigates how confinement affects the flow behavior of non-Brownian suspensions, revealing layer formation and viscosity reduction when channel width is an integer multiple of particle diameter.

Contribution

It demonstrates the self-organization of particles into sliding layers in confined suspensions and quantifies the resulting viscosity changes using direct numerical simulations.

Findings

Layer formation occurs at specific channel widths.

Viscosity is significantly reduced in layered configurations.

Layers exhibit liquid-like structure but frozen dynamics.

Abstract

We study the rheology of confined suspensions of neutrally buoyant rigid monodisperse spheres in plane-Couette flow using Direct Numerical Simulations. We find that if the width of the channel is a (small) integer multiple of the sphere's diameter, the spheres self-organize into two-dimensional layers that slide on each other and the suspension's effective viscosity is significantly reduced. Each two-dimensional layer is found to be structurally liquid-like but their dynamics is frozen in time.